


Laundry Duty

by singularweed



Category: Undertale (Video Game)
Genre: Incest, M/M, if you catch my drift, maybe sans will lend him a hand, paps clueless and horny thats all you need to know, sensitive ribs
Language: English
Status: Completed
Published: 2016-01-17
Updated: 2016-01-23
Packaged: 2018-05-14 12:00:40
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 4,400
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5743081
Author URL: https://archiveofourown.org/users/singularweed/pseuds/singularweed
Summary: <blockquote class="userstuff">
              <p>Papyrus is home alone with Sans' jacket. He decides to indulge his... curiosity.</p>
            </blockquote>





	1. horny and confused

**Notes for the Chapter:**

> EDIT: fixed the formatting so it's easier to read. enjoy!

“Oh, you lazybones,” Papyrus muttered, picking up the filthy sock hanging off the armrest of the sofa and adding it to the growing pile on the carpet. How many was that now? Five, six… Eleven… Thirty three. Papyrus didn’t even remember Sans _ owning  _ that many socks. He didn’t even know where they came from. It was almost like Sans could just pull socks out of the void.

Papyrus grimaced and dug his hand into the crevice between the armrest and the seat cushion, feeling around for any strays. His finger snagged on a piece of fabric. 

“Nyah-hah! No mere sock can elude the great Papyrus!” He grasped the fabric and pulled. The cloth didn’t come out. He pulled harder, to no avail. Seemed whatever he was holding was much larger than a sock. It was still stuck in the deep, endless abyss known as their couch.

Papyrus braced both his feet on the floor and yanked as hard as he could. The fabric came flying out of the sofa, causing Papyrus to stumble back a few steps and nearly crash into their T.V.

….That wasn’t a sock. First of all, he had been holding a sleeve. A sleeve attached to a beaten up, baggy, old jacket, complete with an unreasonably fluffy hood. 

Sans’ jacket. 

What was his brother’s coat doing lying around inside the sofa? Sans never took off that jacket. It was practically a part of his body. Sans and his jacket were inseparable, like Papyrus and his battle body, or Alphys and anime, Undyne and violence, Sans and terrible jokes-- well, you get the idea.

Papyrus looked up at his brother’s room. Right. He was still at work.

Papyrus sighed, slinging the jacket over his shoulder and bending over to pick up the massive pile of socks he had amassed. He moved to dump the pile in the laundry basket in front of Sans’ room. He swiftly turned around, intending to make his way to Sans’ station in Waterfall and return his brother’s jacket immediately.

Papyrus took two steps towards the stairs, then stopped. A tempting idea began to tickle the back of his mind. Sans rarely let other people take his jacket. Sans wouldn’t be coming home for a while, and now might be the perfect time for Papyrus to indulge his… curiosity. Papyrus looked at the well-loved jacket in his hands. It would be impossible to look at it and  _ not _ think of Sans. 

Papyrus gripped the jacket close to his chest, a guilty grin creeping onto his face. It wouldn’t hurt to hold onto it a  _ little _ longer. Sans lost it in the sofa, and if it hadn’t been for Papyrus, it wouldn’t have even made it out of that abyss for  _ days _ .

Making up his mind, Papyrus yanked open the door to his room and rushed inside, plopping himself down on his bed. He impulsively lifted the bunches of fabric to his face and inhaled. Smelled like… Sans. It smelled like pine needles, echo flowers, and… bones. Somehow, the clash of scents melded together into something familiar and strangely pleasant.

Papyrus let his eyes flutter closed and he took several more deep breaths. It was almost like Sans was there with him, in Papyrus’ arms… Just the two of them, together. Papyrus let his mind wander to his brother. Even though Sans  _ was _ lazy and messy, he was still really great. He always had time for Papyrus, whether it was just hanging around while Papyrus made his puzzles, or taking the time to eat his pasta. And Sans would always look at him in that way, too, when he thought Papyrus couldn’t see. That distracted and heated expression he got sometimes whenever Papyrus was honed in on work. Papyrus didn’t really understand why Sans looked at him that way, but… it always made his soul feel like it was about to jump right out of his ribcage. Unthinkingly, Papyrus’ hand wandered down to his hips, and he began to trace small patterns over the outside of his pelvis.

“Ah… Mmpph--!”

Papyrus’ eyes snapped open. He absolutely did  _ not _ mean to do that. Okay. Recap. He was thinking about his brother: how he was always there for him, how his hugs would be the best feeling in the world because somehow he always felt so soft, even though he was literally just clothing and bones, and then Papyrus’ thoughts got carried away and he had his hand on his pelvis and his face buried in Sans’ jacket and -- no.

Maybe the question wasn’t  _ why _ he did it, but why it felt so  _ good _ .

Papyrus clenched the jacket in between his hands. This was strange, but it was a good strange. A very good strange. He wasn’t sure if he wanted to stop.

He wondered what the jacket would feel like against his own bones.

Feeling a vague sense of guilt over his shoulders, Papyrus shrugged on the jacket. It was a little small, but it was baggy and still fit over Papyrus’ larger frame.

Papyrus suddenly had the urge to giggle. The jacket was really comfortable, and he was reminded again of those rare hugs he would get from Sans. The hugs that would make his soul feel like it would fly out of his chest, those hugs that made him feel warm at his core for no apparent reason. Sans wouldn’t hug him very often. He’d always start, then excuse himself really quickly. He said it was something about his “magic acting up,” then he’d run to his room and slam the door shut. Weird.

Papyrus stared down at his own pelvis. Whatever he had done earlier, it felt good. The same kind of good he felt when Sans hugged him. Maybe, if he thought of that feeling  _ while _ touching his own bones, it would feel even better…?

Papyrus pulled the jacket up close to him and let his hand trail down his spine again. The sensation sent sparks through his body, and he tried not to gasp. What if… Papyrus lifted his shirt a little and slid one finger across one of his lower ribs. 

_ Oh _ .

Papyrus bit down on the collar of the jacket and continued touching his ribs. Who knew they would be so… sensitive? Papyrus closed his eyes again and rubbed lightly between the thin bones. Papyrus felt a warm wave of pleasure pulse through his body. What if  _ Sans _ was the one doing this for him instead? Sans was good at a lot of things, even if he didn’t try very often. He always said he’d be willing to try things for Papyrus, though. Maybe Papyrus would ask him about this when he got home. Yeah, that would be a good idea.

Papyrus hunched over and pulled the jacket’s hood over his head, using one hand to trace his ribs and the other to rub the inside of his pelvis. Papyrus gasped and ground his teeth. He still wasn’t entirely sure what he was doing, or why it felt good. He just knew he needed to keep doing it.

Papyrus huffed and moved his hand more aggressively against his bones. If he had skin, he would’ve broken into a sweat by now. For some reason, his thoughts kept drifting back to Sans. Sans and those stupid looks he’d give him, Sans and his unfairly soft body, Sans with that lazy expression he  _ knew _ drove Papyrus crazy, and...

Papyrus’ breath hitched. Something strange was happening, and Papyrus had no intention of stopping it. He put his head down, firmly stroking his ribs. He felt so close to something-- he needed to touch just a little bit more, and- ah. 

Something flexible and wet curled out of Papyrus’ mouth and dripped flecks of orange liquid onto Sans’ jacket.

“Wh---”

Papyrus brought his hands to his mouth and looked down at this new development. Just in his sight of view hung a long, supple tongue in a bright orange hue. Papyrus felt a blush creep onto his face. A while back, Sans had tried to teach him how to summon body parts using magic. He said that tongues were some of the easiest things to conjure, but when Papyrus managed to succeed, Sans stopped the lesson abruptly and left to do who-knows-what in his room again.

Papyrus’ face felt warm. This time, the tongue had materialized completely involuntarily. Did it come as a response to Papyrus… touching himself?

A tremor shot through Papyrus’ body, and he shuddered. Looks like that pent-up feeling of pleasure didn’t dissipate after his tongue formed. If anything, the need to relieve it just felt  _ more  _ unbearable. He could think later. For now, he just needed to abate this urge. Figuring out magic tongues was  _ not _ a priority.

Papyrus hastily shoved a few fingers between his ribs again and moved them roughly. He knew he could do this in a much neater, less animalistic way, but honestly, he just needed to  _ move _ . His tongue lolled out of his mouth, dribbling saliva over Sans’ jacket and Papyrus’ ribs. Papyrus groaned, continuing his unrefined movements.

Yes, yes, yes. He was getting close to something, he could feel it…! On impulse, Papyrus stuck two of his fingers inside his mouth. He felt his tongue pressed up against them, and the feeling only amplified the pleasure he was feeling. He arched his back in bliss. His thoughts became cloudy; that tension deep inside him was about to unravel-

“Haah-- ngh, S-Sans!”

_ Zwoop! _

“You called?”

Uh oh.

  
  
  
  
  


**Notes for the Chapter:**

> part 2, the post sequel: sans is fucking horny too- coming soon 
> 
> thanks for reading. leave kudos and comments if you want to see more. stay classy, you sinners


	2. chapter 2, the post sequel: sans is fucking horny too

**Summary for the Chapter:**

> Papyrus is found out. Sans is prepared to give him some hands-on education.

**Notes for the Chapter:**

> thank you all for the attention youve given this sinful little fic! your kudos sustain me. comments keep the sin flowing freely. i read every single one and physically vibrate. keep em coming. i love them all.

Sans wanted to smack himself in the face for that opener. Oh yes, when your brother screams your name in the heat of arousal, the obvious response is to teleport right outside his door and casually say “You called?” Great thinking there, Sans.

Sans would have dumped himself in the shame corner within seconds if it wasn’t for the… busy sight in front of him.

Papyrus looked utterly helpless. His legs were splayed out as he desperately ground against his sheets like an animal in heat. Orange saliva leaked out of his mouth, sliding down his fingers and onto Sans’ jacket. Papyrus’ other digits worked furiously at his ribs, pumping between the slim bones roughly.

Sans’ soul throbbed. While Papyrus was doing these filthy things to himself, he moaned Sans’ name.

Sans felt like he needed to pass out, or maybe come right on the spot. Probably both.

“S-Sans?”

Definitely both.

Sans’ face warmed, and he hopelessly tried to contain his magic from acting up. He couldn’t let it form. He wouldn’t allow it. Now if only it would stop collecting around his pelvis and shaping into-

“S-Sans! Go away!” Papyrus slowed his movements, but he didn’t stop. It seemed he was incapable of stopping at this point.

Sans opened his mouth, and closed it again. Words failed him.

Papyrus’ hips jerked uncontrollably against his sheets, and he turned his head away from Sans. “Don’t look at me right now-- I’m- hnngh- u-undignified and indecent and-- hah!” Papyrus threw his head back and gasped.

Fuck it. 

Sans exhaled and began palming at the front of his shorts. This was practically a fantasy come true. He wouldn’t just let it go to waste without treating himself a little. How many times had he imagined a scenario like this? How many times had he run off to his room, slamming the door shut and jerking off to his brother? His brother, with those stupid hugs that would make Sans feel hot all over for no reason. That intense expression Papyrus got when he worked; the expression that screamed dedication and strength. And of course, how could he forget the time when he taught Papyrus to summon body parts with magic? He shaped that slick, beautiful tongue within two attempts. Sans couldn’t even stick around long enough to be proud of him, because the only thing running through his mind was the thought of how that tongue would feel wet, dripping, and flush against his cock.

And now, that tongue was hanging out of Papyrus’ mouth as he pleasured himself and moaned like a slut.

Papyrus’ comfort was still his top priority, though. He couldn’t forget that. Sans had to make sure he was okay. Sans braced himself against the doorframe and struggled to try and say anything, but his mind couldn’t focus. His arousal tugged at his magic, and it was taking all his concentration just to keep it in check. Self control, Sans, he chided himself. Don’t let your urges impact others.

“Paps, I, uh- You...” Dammit, Sans! Why couldn’t he just talk?  
Papyrus looked back at his brother. Luminescent tears threatened to leak out of his eyesockets.

“Brother… Don’t- ghh- don’t look at me, please! I’m exposed and… Hah… I don’t know what’s happening. I feel- I feel-”

Sans struggled to compose himself. “How do you feel?”

“I feel warm all over, and something’s- something’s happening to me, and I really need it to happen! I just want… help…. Help me, Sans… Please, hah… Help me…”

That was it. Papyrus was asking- no, begging Sans to help him. Sans cursed himself, trying to block out the possible scenarios his mind spawned. He had to focus, no matter how damn tempting his brother was.

Sans struggled to take a step forward, using one hand to conceal the… predicament in his shorts. “Breathe, Paps. I’m here for you.”

Papyrus was still shaking. Muffled whimpers escaped from him, and he faced Sans. A pretty golden blush painted his cheekbones. ”Sans, what’s happening?”

Sans tried to look his brother in the eyes, but his attention kept being drawn back down to the... distraction hanging out of Papyrus’ mouth.

“Uh, well. You’re just… worked up, is all. It’s natural. You just need to satisfy yourself, then it’ll all be over.”

“Satisfy myself? How?”

Sans gulped. This wasn’t happening. There was no way this was real. Everything in Sans’ mind screamed for him to stop, but he kept running his mouth, as usual.

“Ah, well, there’s a lot of ways, but…” Sans took a deep breath. “I could… show you?” Wow. He was on a roll. This was the second time he wanted to slap himself in the past five minutes.

“Show me, please!” The nervousness in Papyrus’ voice bled away and was replaced by giddy excitement.

Sans couldn’t believe he was doing this. He was supposed to be helping Papyrus, not indulging himself. Papyrus did ask, though, and who was Sans to refuse? Sans steeled himself. He was doing this for him.

Sans focused, drawing from the energy in his soul and concentrating it in his mouth. A sloppy, effervescent blue tongue materialized, filling the empty space in his jaw. A couple blue drops of saliva slid off. Sans silently cursed himself. He wished he had as much control over his magic as Papyrus did. Sans never could form it perfectly; the tongue always ended up unrefined and wet. A blush threatened Sans’ cheekbones, and he turned his gaze away from Papyrus.

Bad idea.

If Sans was looking, he would’ve seen what was coming next.

He would’ve seen Papyrus stare at Sans’ tongue with a look of want. One could even call it a look of lust. If Sans was looking, he would’ve seen the exact moment when Papyrus’ expression changed from uncertainty and confusion to undiluted determination.

Papyrus grasped the front of Sans’ shirt and pulled him near. For a split second, they made eye contact; energy sparked and fizzled in Sans’ soul. Then, Papyrus closed the gap, pushing their tongues together.

“Mm-mpph!”

Sans gasped into the kiss. Papyrus brought him in closer, forcing their mouths together into a heated dance. The kiss was clumsy and desperate, but it sent heat to Sans’ core. He leaned in and kissed back, feeling around Papyrus’ mouth. Doubt ghosted his mind for a moment, but it was swiftly crushed under overwhelming want. He wouldn’t pass up this opportunity. He grinned, an idea lighting up in his head. Sans slid one hand under Papyrus’ shirt and started stroking his ribs. His reply was a delicious moan, and he continued his intrusive touches. Exhilarated at Papyrus’ willingness, Sans deepened the kiss. God, when did Papyrus get so bold? Sans felt drunk with pleasure. Papyrus made the first move, and it was certainly a strong one. The mere fact that Papyrus initiated it struck him deep- in a good way. Lost in the moment, he canted his hips forward and ground on Papyrus. Hard.

Papyrus abruptly pulled away from Sans.

Oh no. Sans shouldn’t have done that. Red alarms flashed in his head. He just rutted his damn cock against Papyrus. He was probably disgusted. Sans had this one opportunity, and of course he’d messed it up with his fucking stupid magic dick-

A hand grasped at the band of his shorts and pulled them down in one swift movement, exposing Sans’ shaft to the open air.

Before Sans even had enough time to register what happened, a curious finger grazed the head of his cock, wiping away the liquid beading at the top. The simple gesture, simply for the fact that it was so unexpected, sent shocks of pleasure flying through Sans. He tossed his head back, mouth agape.

“What’s this, brother?” A brief look of concern flashed across Papyrus’ face. “Oh no! Did I hurt you?”

Sans ground his teeth. His breaths came fast and shallow. “No, Paps. It didn’t hurt. It- it felt good.”

Papyrus’ face lit up. “Oh, well if that’s the case, then I should keep touching it, right? To make you feel good! What did you say earlier? To ‘satisfy’ you?” Papyrus wrapped his hand around Sans’ cock and slid his hand down in one fluid motion.

Sans almost choked. He had to be dreaming. Well, maybe not. This was far more surreal than anything his imagination could cook up.

“How about that, Sans? You said that I needed to satisfy myself, but it looks like you need to be satisfied, too! Am I doing it right?”

All Sans could manage was a weak nod. Papyrus always was a fast learner, damn him, and only he would take action so quickly.  
Papyrus panted, tenuously tracing his own pelvis as he slowly pumped Sans. An orange glow began to collect around his coccyx, but it dissipated just as quickly. Papyrus groaned. Sans couldn’t tell if it was from arousal or frustration, or both. Papyrus’ hand slid down on Sans’ cock again, and a hushed growl escaped him. For someone who didn’t even know what a dick was, Papyrus sure was proficient at making him feel good. Speaking of that… Though his thoughts were hazy, Sans understood what Papyrus was trying to do for himself.

“Paps, do you… want one, too?”

The blush that tinged Papyrus’ cheekbones deepened. “Y-yes… It looks like you’re having a lot of fun with… Uh, what is it called?”

Sans chuckled. “Ah, uh. It’s a dick, Paps. Or a penis, or cock, or, you know. It helps you feel good.”

Papyrus nodded energetically. His hand squeezed at Sans’ member, eliciting another muffled moan. “I get it! How do I get it to form?” Sans clenched his teeth together. Papyrus was not making it easy for him to stay collected and rational.

“You just gotta… It’s like your tongue. If you just feel hard enough, and know what you want it to be, it’ll just happen. In fact…” Sans gingerly backed away from Papyrus. His brother whined in response. “Don’t worry, bro. I’m gonna help you get it to form.” Sans took a deep breath, and knelt on the floor in front of Papyrus.

“B-brother? What are you doing?” Papyrus asked. His voice was hushed.

“Just let it happen, Paps.” Sans eyed his brother’s pelvis. Small wisps of golden magic collected and dispersed at random. Perfect.

Sans leaned in and licked a long stripe up Papyrus’ sacrum, reveling in the broken gasp he heard as a response. Soon, most of Papyrus’ pelvis was drenched in luminescent, translucent blue liquid. Sans methodically pumped his own dick as his mouth was occupied.

Sans wondered if he was doing a good job. He felt every texture and groove with his tongue, trying to be as thorough as possible. Judging from the overflow of noises escaping Papyrus, it seemed Sans was succeeding.

The magic resonating around Papyrus’ hips began to glow brighter, condensing right in front of Sans’ face. Ah, just what he wanted. Sans turned his attention to the forming magic, sweeping his tongue over it.

“S-Sans! Something’s happening!”  
Sans glanced up at his brother for a moment, simply smirking and leaning in even closer. He swirled his tongue around the bone where Papyrus’ magic was collecting.  
Papyrus’ hand grasped the back of Sans’ head and pushed him even closer. Sans mewled in surprise but obliged.

Papyrus pushed his hips forward. Suddenly, Sans’ mouth wasn’t so empty anymore. Something pressed right against his tongue and reached into the back of his mouth. A stifled cry escaped Sans. The unexpected size and girth of the member occupying his mouth caught him off guard. He didn’t back away, though. He simply sunk his mouth fully onto Papyrus. He choked slightly, and heat shot straight to his own aching cock.

“Ah-Ahh! That’s-!” Papyrus bit down on the collar of Sans’ jacket again to stop himself from vocalising.

That wouldn’t do. Sans wanted to hear him.

Sans brought his head back, almost completely letting go of Papyrus’ cock, before hastily swallowing down the whole length again. He bobbed his head, occasionally letting out a moan of satisfaction. He swirled his tongue around the tip, paying excruciating attention to making Papyrus feel good.

And feel good he did.

Papyrus was ravaged. The suddenness of the whole situation combined with Sans’ overwhelming attention overstimulated him, and Sans could see it. Papyrus was a slave to his own libido, but… Sans was no better. The tension coiling in him built up, stronger and stronger. He jerked off his cock aggressively, bobbing his head on Papyrus’ dick in rhythm with his own movements.

Papyrus couldn’t stop the sounds spilling out of him anymore. He gasped and mewled. His sounds of delight were even punctuated with the occasional growl. He clutched at Sans’ head, pushing him to sink even deeper onto him. Sans was more than willing.

“S-Sans! I- Nnngh- Hff, hnn- I- Oh, you’re so good, Sans.”

Sans hummed happily. Drool leaked excessively out of his mouth, but he couldn’t care less. He was in utter rapture. Precum dribbled out of his cock. He was getting close, and it looked like Papyrus was, too.  
Papyrus jerked his hips forward, thrusting into Sans’ mouth. Sans let him in willingly, slicking him up with his tongue.

“Hahh- Sans, I’m getting close! Hnn… Sans!”

Papyrus shuddered and thrust a few last times into Sans’ mouth. Warm liquid gushed into Sans’ mouth, some leaking out the sides. Sans stroked his own cock, moving forward into his hand roughly. He shook, his mouth opening in a small “O” before coming himself. Some of the blue liquid splattered onto Sans’ own ribs and rolled down in droplets.

Papyrus gave a few more weak thrusts in Sans’ mouth before pulling out. Sans caught a quick glimpse of his member. It looked, well, just like Sans’. But it looked like Papyrus had ended up… endowing himself a little more. Sans noted it for future occasions.

Both of the brothers’ magic dissipated, leaving behind only the more physical parts, which happened to include the gratuitous amounts of ectoplasm glazed over Sans’ bones, the sheets, Sans’ coat, and- Well. It was everywhere.

Papyrus let out a satisfied sigh and fell back on his bed. Sans crawled up to lie down next to him, and both brothers lay in comfortable silence for a while. Normally, a billion thoughts would be blazing through Sans’ head, but he honestly just felt complete and satisfied. He reached over to hold Papyrus’ hand. He got a soft squeeze in return.

A soft “nyeh-heh-heh” sounded from next to Sans. He smiled, looking at his brother and raising a figurative eyebrow. “Hm? What was that, Paps?”

Papyrus grinned and looked up at the ceiling. “I’m really glad we did that,” he said, holding Sans’ hand tighter. “It was confusing at first, but… It felt really nice.”

Shit. He was too damn cute.

Sans managed to laugh softly as well. “Well, to be honest, I was surprised this all even happened.”

“Me too.” Papyrus paused. “So, is this what you do whenever you run to your room?”

Sans felt his face burning. “Uh, heh, yup. Because- because of you.”

Papyrus rolled over and faced Sans, his eyes lighting up. “Really? You did that because of me?”

“Well, of course.” Sans rubbed the back of his head. “I… really wanted to do that. For a long time.”

Papyrus contemplated a bit. “Well, I did it because of you, too. I don’t know where it came from, but… I was cleaning, then I had your jacket, then suddenly I had a bunch of thoughts and they were really, really good thoughts! Then you came and made it even better.”

So much for hugs making Sans feel like his soul was going to fly out of his body. Currently, his soul felt like it was about to board a rocket ship and launch into outer space.

“You made it better for me, too.” Sans sighed contentedly. Everything felt warm and floaty and light.

Papyrus shifted beside him. “But wait, Sans! I still have your jacket. Right here.” Papyrus shrugged off the jacket and moved to pass it to Sans. It was wrinkled, had blue and orange stains covering it, and basically, just looked completely wrecked. Sans let out a short laugh. Papyrus rubbed the side of his head.

“Nyeh heh, I don’t think you can wear it right now, though. It’s a little… messy.”

“Heh, sure is. Hey, what happened to all my socks, anyway?”

Papyrus huffed. “Oh, your thirty-three non-matching socks? I picked them all up while you were at work, you lazybones.”

Sans chuckled. “You counted them? God, Paps. Thanks.” Sans felt a weak shove to his shoulder, and he laughed lightly. He deserved that.

Papyrus sighed dramatically, balling up the jacket under his arm. “Come on, Sans. We should clean up. Let’s go do our laundry.”

**Notes for the Chapter:**

> and there we have it, folks.  
> now. there's more fontcest in the works. but i must ask: what would you like to see first? an underfell fic, with roughness and possessiveness? a desperate and loving underswap skeleheat? other suggestions?  
> comment. its what inspires me to do more.  
> oh yeah, and if you want to come scream at me, you'll find me at smoochthemskeles.tumblr.com. my partner serif and i sin there. feel free to shoot us some asks.  
> again, thanks for reading, and stay classy, you sinners.


End file.
